Information playback systems frequently utilize a stylus for reading signals from the surface of an information record, typically a plastic disc, that contains stored video and audio information. In some systems the information record has a fine spiral groove to guide the tip of a stylus that contains a thin electrode. In these systems, the stylus tip is typically micromachined from natural or synthetic diamond. The stylus tip is tapered to form the prow of the tip, and is also lapped to form a keel having a V-shaped shoe for its bottom portion. This keel-shaped tip has a shoe length of about 3 to 4 micrometers and a thickness of about 2 micrometers.
In manufacturing stylus tips for use in such video disc playback systems, the tip of the diamond stylus is inspected with a high-power optical microscope havihg 1000.times. to 1500.times. magnification. Since the field of view of such an instrument is so small, it is laborious and time consuming to bring the stylus tip into focus by manual adjustments. One possible method for facilitating alignment of the stylus tip is to insert the tip into a conical or grooved structure, made of glass, for guiding the tip into the field of view. An index-matching immersion oil is utilized to permit high-resolution examination of the tip through the glass structure. Such a method not only raises the possibility of mechanical damage during the alignment, but necessitates removal of the immersion oil after the inspection has been made. The present invention provides a novel method and apparatus for rapidly and automatically positioning a tapered stylus tip which does not require any contacting of the tip.